Here's a breakdown:
* Vadi: This is the most important note of the raga, the one that defines its character and flavour. It's often the note that is emphasized in the melodic phrase and acts as a focal point.
* Samvadi: This note is complementary to the Vadi, adding a supporting element to the raga's melody. It's usually a note that sounds pleasing when played in conjunction with the Vadi.
It's important to note that the Vadi and Samvadi are not always the same in every raga. The specific notes used for these two principle tones depend on the individual raga's structure and composition.
Do you want to learn more about how the Vadi and Samvadi affect a raga's sound? I'd be happy to provide further details!